Semi-submerged marine structures generally have such a structure in which a plurality of columns having their respective upper portion projecting above water surface are built on each of a plurality of submerged bodies held in water and, while a platform is supported on and by all the columns, correspondingly located columns on respective submerged bodies are supported in pairs by bracings.
Then, according to the prior art, the bracing is secured with its portion having a larger cross-sectional area to the column in a manner such that a connection portion of the bracing at which the portion having a larger cross-sectional area and a tapering portion are connected to each other is disposed outside the column, so that the problem is encountered that stress concentrates at the connection portion to produce cracking therein.
The present invention aims at avoiding the concentration of stress at the connection portion in or of the bracings.